Vehicle seat

ABSTRACT

A vehicle seat comprising: a seat cushion; a seat back; an actuator capable of changing an orientation of the seat back laterally by moving a pressure-receiving member; and a controller configured to exercise control over the actuator. The controller includes a posture control unit configured to execute, during turning of a vehicle, a seat posture control under which the actuator is caused to move the pressure-receiving member from an initial position to an advanced position to cause the seat back to orient toward a turning direction. The posture control unit is configured to activate, when an execution time of the seat posture control has become equal to or greater than an execution time threshold value, a control under which the actuator is caused to move the pressure-receiving member from the advanced position to an intermediate position to reversely change the orientation of the seat back.

TECHNICAL FIELD

The present invention relates to a vehicle seat having a capability ofchanging an orientation of a seat back laterally in accordance with astate of a vehicle making a turn.

BACKGROUND ART

A car seat apparatus configured such that when a vehicle turns, anorientation of a seat back is changed by swiveling a back plate portionof the seat back to orient toward a turning direction so as not to allowthe feature of holding an occupant to be impaired due to a lateralacceleration produced in a direction reverse to the turning direction ishitherto known in the art (e.g., Patent Document 1). According to theinvention disclosed in the Patent Document 1, a control exercised issuch that the lateral acceleration to be imposed on the car is estimatedby computation, and when the lateral acceleration exceeds apredetermined threshold value, the orientation of the back plate portionof the seat back is changed.

CITATION LIST Patent Literature

-   Patent Document 1: JP 2013-049357 A

SUMMARY OF INVENTION

In such a configuration that when the vehicle turns, the orientation ofthe seat back is changed to orient toward a turning direction, however,when the vehicle turns for an extended period of time, a long durationof an unusual state of the seat configuration different from the statein normal times would disadvantageously cause an occupant to feeluncomfortable.

It is thus an object of the present invention to provide a vehicle seatthat can be made less likely to cause an occupant to feel uncomfortableeven when the vehicle turns for an extended period of time.

In order to achieve the above object, a vehicle seat according to thepresent invention comprises a seat cushion, a seat back, an actuatorcapable of changing an orientation of a seat back laterally by moving atleast part of the seat back, and a controller configured to exercisecontrol over the actuator, wherein the controller includes a posturecontrol unit configured to execute, during turning of a vehicle, a seatposture control under which the actuator is caused to move the at leastpart of the seat back from an initial position to a first position tocause the seat back to orient toward a turning direction, and whereinthe posture control unit is configured to activate, when an executiontime of the seat posture control has become equal to or greater than anexecution time threshold value, a control under which the actuator iscaused to move the at least part of the seat back from the firstposition to a second position to reversely change the orientation of theseat back.

With this configuration, the orientation of the seat back is reverselychanged when the execution time of the seat posture control has becomeequal to or greater than the execution time threshold value; therefore,even when the vehicle turns for an extended period of time, an occupantcan be made less likely to feel uncomfortable

The vehicle seat as described above may be configured such that thesecond position is between the initial position and the first position.

With this feature, the occupant can be made less likely to feeluncomfortable with a good hold of the occupant being kept during theturning of the vehicle.

The vehicle seat as described above may be configured such that thecontroller includes a lateral acceleration acquisition unit configuredto acquire a lateral acceleration, and the posture control unit may beconfigured to activate, when a magnitude of the lateral accelerationacquired by the lateral acceleration acquisition unit during the turningof the vehicle has become equal to or greater than a first thresholdvalue, a control under which the actuator is caused to move the at leastpart of the seat back from the initial position to the first position.

In the vehicle seat as described above, the posture control unit may beconfigured to activate, when a magnitude of the lateral accelerationacquired by the lateral acceleration acquisition unit during the seatposture control has become equal to or smaller than a second thresholdvalue that is smaller than the first threshold value, a control underwhich the actuator is caused to move the at least part of the seat backto the initial position to thereby bring the seat posture control to anend.

In the vehicle seat as described above, the posture control unit may beconfigured such that a motion from the first position to the secondposition is produced with a speed slower than a speed of a motion fromthe initial position to the first position as produced during startup ofthe seat posture control.

In the vehicle seat as described above, the posture control unit may beconfigured such that a motion from the first position to the secondposition is produced with a speed slower than a speed of a motion to theinitial position as produced during a process of bringing the seatposture control to an end.

The vehicle seat as described above may further comprise apressure-receiving member provided to receive a load from an occupant,the pressure-receiving member being disposed between left and right sideframes that constitute left and right frames of the seat back, whereinthe actuator is configured to change the orientation of the seat backlaterally by moving the pressure-receiving member.

The vehicle seat as described above may be configured such that the seatback includes a central portion allowing a back of an occupant to restthereagainst, and side portions disposed at left and right sides of thecentral portion and jutting frontward farther than the central portion,wherein a gap formed between the central portion and one of the sideportions is greater when the pressure-receiving member is in the secondposition than when the pressure-receiving member is in the firstposition.

With this configuration, an upper body of the occupant can be supportedadequately in this gap. Therefore, the stability of the upper body ofthe occupant during the seat posture control can be improved.

The vehicle seat as described above may be configured such that anamount of actuation of the actuator between the initial position and thesecond position is half an amount of actuation of the actuator betweenthe initial position and the first position.

The vehicle seat as described above may be configured such that theposture control unit is configured to reversely change the orientationof the seat back stepwise in accordance with a lapse of the executiontime of the seat posture control.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a car seat as an example of a vehicleseat according to an embodiment of the present invention.

FIG. 2 is a perspective view of a seat frame incorporated in the carseat.

FIG. 3 is an enlarged perspective view of a posture control mechanismaccording to a first embodiment.

FIG. 4 is a sectional view of a seat back for showing operations of theposture control mechanism and a pressure-receiving member, in which thepressure-receiving member is in an initial position.

FIG. 5 includes sectional views of the seat back for showing theoperations of the posture control mechanism and the pressure-receivingmember: a view (a) in which the pressure-receiving member is in anintermediate position, and a view (b) in which the pressure-receivingmember is in an advanced position.

FIG. 6 is a block diagram for explaining a configuration of acontroller.

FIG. 7 is a flowchart showing process steps executed in the controller.

FIG. 8 is a flowchart showing process steps executed in the controller.

FIG. 9 is a timing chart showing a lateral acceleration, a position ofthe pressure-receiving member, respective flags, and a seat posturecontrol execution time, during a travel of a car.

FIG. 10 is a perspective view of a posture control mechanism accordingto a second embodiment, as viewed from a rear side thereof.

FIG. 11 is a plan view of the posture control mechanism according to thesecond embodiment.

FIG. 12 includes schematic diagrams (a)-(c) for explaining operations ofthe posture control mechanism according to the second embodiment.

FIG. 13 includes schematic diagrams (a)-(c) for explaining operations ofa car seat according to the second embodiment.

FIG. 14 is a plan view of a posture control mechanism according to athird embodiment.

FIG. 15 includes schematic diagrams (a)-(c) for explaining operations ofthe posture control mechanism according to the third embodiment.

FIG. 16 is a perspective view of a seat back frame incorporated in a carseat according to a fourth embodiment.

FIG. 17 is a sectional view taken along a plane extending through aright side frame in a direction perpendicular to the front-reardirection.

FIG. 18 includes a sectional view (a) taken along line A-A of FIG. 17and a sectional view (b) taken along line B-B of FIG. 17.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereafter, a first embodiment of the present invention will be describedin detail with reference made to the drawings where appropriate. In thefollowing description, a mechanical setup of a car seat as one exampleof a vehicle seat will be discussed at the outset, and then aconfiguration for control implemented in a posture control mechanismwill be discussed.

<Mechanical Setup of Car Seat>

As shown in FIG. 1, a car seat S, which is a seat for use in a driver'sseat of an automobile, mainly comprises a seat cushion S1, a seat backS2, and a headrest S3. The seat back S2 includes a central portion S21allowing a back of an occupant to rest thereagainst, and side portionsS22 disposed at left and right sides of the central portion S21 andjutting frontward farther than the central portion S21. It is to beunderstood that the car seat S may be installed not only in the driver'sseat, but also in the passenger seat next to the driver's seat, a rearseat, or any other seat locations.

The seat cushion S1 and the seat back S2 incorporate a seat frame F asshown in FIG. 2. The seat frame F is composed mainly of a seat cushionframe F1 constituting a frame of the seat cushion S1, and a seat backframe F2 constituting a frame of the seat back S2. The seat cushion S1is formed by upholstering the seat cushion frame F1 with a seat cushionpad P1 made of a cushiony material such as urethane foam, and an outercovering U1 made of synthetic leather, fabric or the like. The seat backS2 is formed by upholstering the seat back frame F2 with a seat back padP2 made of a cushiony material, and an outer covering U2 made ofsynthetic leather, fabric or the like (see also FIG. 1).

The seat back frame F2 has a lower portion thereof pivotally connectedvia a reclining mechanism RL to a rear portion of the seat cushion frameF1. This allows the seat back S2 to be tilted frontward and rearwardrelative to the seat cushion S1.

It is to be noted that the directions in this description, i.e.,front/rear (frontward/rearward), left/right (leftward/rightward;lateral) and upper/lower (upward/downward), are designated withreference to an occupant seated on the car seat S in its unreclinedposition such that the seat back S2 is not tilted down by means of thereclining mechanism RL.

The seat back frame F2 is configured to mainly include an upper frame10, left and right side frames 20 and a lower frame 30, and formed inthe shape of a picture frame with the upper frame 10, the left and rightside frames 20 and the lower frame 30 welded or otherwise joinedtogether in one piece.

The upper frame 10 is formed by bending a metal pipe material in asubstantially U-shaped configuration, and includes a lateral pipeportion 11 on which are fixed support brackets 12 for use in attachingthe headrest S3 thereto. The upper frame 10 further includes left andright vertical pipe portions 13 of which lower portions are connected toupper portions of side frame main body portions 21 respectively so thatthe left and right vertical pipe portions 13 together with the sideframe main body portions 21 constitute the side frames 20.

The side frame main body portions 21 are made of stamped or otherwiseformed sheet metal. The side frame main body portions 21 include bulgingportions 22 provided at their lower portions and jutting frontwardfarther than their upper portions to form side portions S22 of the seatback S2.

At an inside of this seat back frame F2 shaped like a picture frame, apressure-receiving member 40 configured to support a back of an occupantand a posture control mechanism 50 configured to change an orientationof the pressure-receiving member 40 laterally (to the left and to theright) are arranged.

The pressure-receiving member 40 is an elastically deformable platemember made of plastic or the like, and is disposed rearward of anoccupant between the left and right side frames 20. To be more specific,the pressure-receiving member 40 includes a pressure-receiving portion41 for supporting the back of an occupant through the seat back pad P2and the like, and support portions 42 protruding from left and rightends of an upper portion of the pressure-receiving portion 41 inlaterally-outward-and-frontward directions. The pressure-receivingportion 41 is located in a position rearward of the central portion S21of the seat back S2, while the support portions 42 are located inpositions rearward of the side portions S22. The support portions 42serve to support an upper portion of the upper body of the occupant fromleft and right sides.

The pressure-receiving member 40 is engaged with, and supported by anupper connecting wire W1 and a lower connecting wire W2 which aredisposed rearward of the pressure-receiving member 40. The upperconnecting wire W1 has its both end portions engaged with and supportedby the posture control mechanisms 50, and the lower connecting wire W2has its both end portions engaged with and supported by wire mountportions 23 provided at laterally inner sides of the left and right sideframes 20.

The posture control mechanism 50 is disposed at each of left and rightsides of the pressure-receiving member 40, and configured to be capableof changing an orientation of the seat back S2 laterally by moving thepressure-receiving member 40 that is part of the seat back S2 undercontrol of a controller 100 (see FIG. 6) which will be described later.

As shown in FIG. 3, the posture control mechanism 50 mainly includes anactuator 51, a retaining bracket 52 (52A, 52B), a first link member 53,a second link member 54, and a torsion spring 55.

The actuator 51 is a source of driving power for causing the first linkmember 53 and the second link member 54 to swing, including a steppingmotor MA that can be rotated in normal and reverse directions, a gearbox 51B, and an output shaft 51C, which are arranged in such a mannerthat the output shaft 51C is positioned to have its axial directionaligned with an upward-downward direction. The actuator 51 is fixed tothe side frame 20 by the retaining bracket 52. The driving power fromthe stepping motor 51A is transmitted with a speed reduced in the gearbox 51B, to the output shaft 51C, to cause the output shaft 51C torotate.

The first link member 53 is an elongated plate member, and has one endportion thereof fixed to the output shaft 51C of the actuator 51, sothat the other end portion thereof can be swung on the output shaft 51Cfrontward and rearward.

The second link member 54 has one end portion pivotally connected to theother end portion of the first link member 53 via a pin 54A so that thesecond link member 54 can swing relative to the first link member 53. Atthe other end portion of the second link member 54, a connecting hole54B in which the end portion of the aforementioned upper connecting wireW1 is pivotally engaged, and a plastic contact portion 54C configured tocontact the pressure-receiving member 40 are formed.

The torsion spring 55 has one end thereof engaged with the first linkmember 53 and the other end thereof engaged with the second link member54, to thereby bias and press the second link member 54 in a clockwisedirection as viewed from above against the first link member 53.

In the description given herein, the right posture control mechanism 50shown in FIG. 3 has been described, and it is to be understood that theleft posture control mechanism 50 is laterally symmetric to the rightposture control mechanism 50.

As shown in FIG. 4, the pressure-receiving member 40 in normal times isoriented frontward, i.e., located in the initial position. In thisstate, a support surface S23 provided on the seat back S2 to support anoccupant is oriented frontward, too.

For example, when the car (vehicle) turns left, the stepping motor 51Aof the right posture control mechanism 50 rotates in the normaldirection under the control of the controller 100, the first link member53 swings frontward, and the second link member 54 swings, so that theright end portion of the pressure-receiving member 40 moves from itsinitial position frontward. Accordingly, the right end portion of thepressure-receiving member 40 moves through an intermediate position asan example of a second position as shown in FIG. 5(a) to an advancedposition as an example of a first position as shown in FIG. 5(b), sothat the pressure-receiving member 40 as a whole is caused to orientleftward (i.e., toward a turning direction). As the seat back pad P2 ispushed out by the right end portion of the pressure-receiving member 40,the support surface S23 of the seat back S2 is caused to orientleftward, as well. In this state, a gap D3 formed between the centralportion S21 and the right side portion S22 of the seat back S2 hasbecome smaller than a gap D1 formed therebetween when thepressure-receiving member 40 is in the initial position.

On the other hand, when the orientation of the seat back S2 is reverselychanged, the stepping motor 51A of the right posture control mechanism50 rotates in the reverse direction under the control of the controller100, the first link member 53 swings rearward, and the second linkmember 54 swings, so that the right end portion of thepressure-receiving member 40 moves from the advanced position rearward.Accordingly, the right end portion of the pressure-receiving member 40moves through the intermediate position as shown in FIG. 5(a) to theinitial position as shown in FIG. 4, so that the pressure-receivingmember 40 as a whole is caused to orient frontward. As a result, thesupport surface S23 of the seat back S2 is caused to orient frontward,as well.

The pressure-receiving member 40 is also configured to be kept in theintermediate position as shown in FIG. 5(a) by stopping the rotation ofthe stepping motor 51A halfway under the control of the controller 100.The intermediate position is between the initial position as shown inFIG. 4 and the advanced position as shown in FIG. 5(b). In the presentembodiment, by way of example, an amount of actuation of the actuator 51between the initial position and the intermediate position is set to besubstantially half an amount of actuation of the actuator 51 between theinitial position and the advanced position. When the right end portionof the pressure-receiving member 40 is in the intermediate position, agap D2 formed between the central portion S21 and the right side portionS22 of the seat back S2 is smaller than the gap D1 formed therebetweenwhen the pressure-receiving member 40 is in the initial position, but isgreater than the gap D3 formed therebetween when the pressure-receivingmember 40 is in the advanced position.

When the car turns right, the stepping motor 51A of the left posturecontrol mechanism 50 rotates in the normal direction under the controlof the controller 100. Subsequent steps of operation are similar tothose described above as for the left-turn situation, and thus adetailed description is omitted.

<Configuration for Control of Posture Control Mechanism>

As shown in FIG. 6, the controller 100 mainly includes a lateralacceleration acquisition unit 110, a posture control unit 130, and astorage unit 190, in order to exercise control over actuation of theactuator 51 to move the pressure-receiving member 40, thereby changingthe orientation of the seat back S2 laterally (to the left or to theright). The controller 100 includes a CPU (central processing unit), aROM (read only memory), a RAM (random access memory) and other moduleswhich are not illustrated in the drawings, and implements the respectiveunits by loading and executing relevant programs pre-stored in thestorage unit 190.

The lateral acceleration acquisition unit 110 is a unit for acquiring alateral acceleration imparted to a car, and is configured in the presentembodiment to acquire a lateral acceleration by computation based on acar speed and a steering angle. To be more specific, the lateralacceleration acquisition unit 110 may work out a lateral acceleration GCby computation based on a wheel velocity acquired from a wheel velocitysensor 91 and a steering angle acquired from to a steering angle sensor92. As an example, the lateral acceleration GC may be computed using thefollowing equations with a car body velocity V determined from the wheelvelocity by a known method and using a stability factor A as a constantspecific to the car, a wheel base L of the car, a steering angle φ, anda turning radius R:R=(1+AV ²)/(L/φ)GC=V ² /R

It is to be understood that, in the present embodiment, the steeringangle φ is taken from the angle of the steering operation of thesteering wheel, but may be taken, for example, from the angle of theturning motion of the car wheel(s) instead if the constants are changed.It is also to be understood that the lateral accelerations GC directedto the right and to the left are represented herein, respectively, bypositive and negative values.

The posture control unit 130 is a unit for executing, during turning ofthe car, a seat posture control under which based on the lateralacceleration GC acquired by the lateral acceleration acquisition unit110 the actuator 51 is caused to move the pressure-receiving member 40,thereby causing the support surface S23 of the seat back S2 to orienttoward the turning direction. To be more specific, the posture controlunit 130 is configured to activate the seat posture control when amagnitude (absolute value) of the lateral acceleration GC has becomeequal to or greater than a first threshold value GCth1; under the seatposture control exercised over the actuator 51, the stepping motor 51Ais caused to rotate in the normal direction to thereby cause thepressure-receiving member 40 to move from the initial position as shownin FIG. 4 to the advanced position as shown in FIG. 5(b).

In the present embodiment, each of the threshold values is predeterminedthrough a test driving, simulation, or the like. In describing thepresent embodiment, it is assumed that GCth1 is a positive value, andwhen the lateral acceleration GC directed leftward as exhibited in theright-turn is assumed to be negative, the magnitude of the lateralacceleration GC being equal to or greater than the first threshold valueGCth1 is represented as GC≤−GCth1.

The posture control unit 130 is configured to reversely change theorientation of the support surface S23 of the seat back S2 when anexecution time of the seat posture control has become long, i.e., equalto or greater than a predetermined period of time. To be more specific,the posture control unit 130 is configured to activate a control overthe actuator 51, when the execution time TE of the seat posture control(in the present embodiment, by way of example, the execution time refersto the a period of time elapsed since the magnitude of the lateralacceleration GC has become equal to or greater than the first thresholdvalue GCth1) has become equal to or greater than an execution timethreshold value TEth, under which control the stepping motor 51A iscaused to rotate in the reverse direction to move the pressure-receivingmember 40 from the advanced position as shown in FIG. 5(b) to theintermediate position as shown in FIG. 5(a). Accordingly, theorientation of the support surface S23 of the seat back S2 is changedreversely toward the orientation in normal times. To be more specific,the angle formed by the support surface S23 with respect to thefront-rear direction becomes an angle which is greater than an angle(=0) formed when the pressure-receiving member 40 is in the initialposition, but smaller than an angle formed when the pressure-receivingmember 40 is in the advanced position. The execution time thresholdvalue TEth may be set appropriately in accordance with thecharacteristics of the car, and may for example be on the order of 3.0secs.

The posture control unit 130 is also configured to bring the seatposture control to an end when the magnitude of the lateral accelerationGC during the seat posture control has become equal to or smaller than asecond threshold value GCth2, by activating a control over the actuator51, under which the stepping motor 51A is caused to rotate in thereverse direction to move the pressure-receiving member 40 from thecurrent position (advanced or intermediate position) to the initialposition as shown in FIG. 4.

In the present embodiment, it is assumed that GCth2 is a positive value,and when the lateral acceleration GC is negative, the magnitude of thelateral acceleration GC being equal to or smaller than the secondthreshold value GCth2 is represented as GC≥−GCth2. The second thresholdvalue GCth2 is set to be a value smaller than the first threshold valueGCth1. For example, the first threshold value GCth1 may be on the orderof 2.0 m/s², the second threshold value GCth2 may be on the order of 1.0m/s².

The storage unit 190 is a device configured to store values acquiredfrom the respective sensors, lateral acceleration values computed by thelateral acceleration acquisition unit 110, and set values such asthreshold values.

Next, one example of process steps executed by the controller 100 willbe described with reference to FIGS. 7 and 8. It is to be understoodthat flowcharts in FIGS. 7 and 8 show the process performed when a carturns left (herein, the lateral acceleration GC is assumed to bepositive), in which a series of steps from START to END are executediteratively for each predetermined control cycle (time interval TU). Ina first flag FL1, 0 is set when the seat posture control is not beingexecuted, and 1 is set when the seat posture control is being executed.In a second flag FL2, 1 is set when the pressure-receiving member 40 isin the intermediate position, and 0 is set when it is in any otherposition. The pressure-receiving member 40 in normal times is in theinitial position, and the initial values of the first flag FL1 and thesecond flag FL2 are 0.

As shown in FIG. 7, the lateral acceleration acquisition unit 110acquires values from the wheel velocity sensor 91 and the steering anglesensor 92 (S101), and computes a lateral acceleration GC from theacquired wheel velocity and steering angle (S102). The posture controlunit 130 then determines whether or not the first flag FL1 is 1 (S111).

If the first flag FL1 is not 1 (i.e., the seat posture control is notbeing executed) (No in S111), then the posture control unit 130determines whether or not the magnitude of the lateral acceleration GCis equal to or greater than the first threshold value GCth1 (S121). Ifthe magnitude of the lateral acceleration GC is not equal to or greaterthan the first threshold value GCth1 (No in S121), then the posturecontrol unit 130 brings the current control cycle to an end.

On the other hand, in step S121, if the magnitude of the lateralacceleration GC is equal to or greater than the first threshold valueGCth1 (Yes in S121), then the posture control unit 130 causes the rightactuator 51 (stepping motor 51A) to rotate in the normal direction, tomove the pressure-receiving member 40 from the initial position (seeFIG. 4) to the advanced position (see FIG. 5(b)) (S122). When the motionto the advanced position is completed (Yes in S123), then the posturecontrol unit 130 sets 1 in the first flag FL1 (S124), and proceeds tostep S151.

In step S111, if the first flag FL1 is 1 (i.e., the seat posture controlis being executed) (Yes in S111), then as shown in FIG. 8, the posturecontrol unit 130 determines whether or not the second flag FL2 is 1(S131).

If the second flag FL2 is not 1 (i.e., the pressure-receiving member 40is in the advanced position) (No in S131), then the posture control unit130 determines whether or not the execution time TE of the seat posturecontrol is equal to or greater than the execution time threshold valueTEth (S141). If the execution time TE is not equal to or greater thanthe execution time threshold value TEth (No in S141), then the posturecontrol unit 130 adds a time TU to the execution time TE to incrementthe execution time TE (S142), and proceeds to step S151. On the otherhand, in step S141, if the execution time TE is equal to or greater thanthe execution time threshold value TEth (Yes in S141), then the posturecontrol unit 130 causes the right actuator 51 (stepping motor 51A) torotate in the reverse direction, to move the pressure-receiving member40 from the advanced position (see FIG. 5(b)) to the intermediateposition (see FIG. 5(a)) (S143). When the motion to the intermediateposition is completed (Yes in S144), then the posture control unit 130sets 1 in the second flag FL2 and resets the execution time TE to 0(S145), and proceeds to step S151.

In step S131, if the second flag FL2 is 1 (i.e., the pressure-receivingmember 40 is in the intermediate position) (Yes in S131), then theposture control unit 130 proceeds to step S151.

Referring back to FIG. 7, in step S151, the posture control unit 130determines whether or not the magnitude of the lateral acceleration GCis equal to or smaller than the second threshold value GCth2 (S151). Ifthe magnitude of the lateral acceleration GC is not equal to or smallerthan the second threshold value GCth2 (No in S151), then the posturecontrol unit 130 brings the current control cycle to an end.

On the other hand, if the magnitude of the lateral acceleration GC isequal to or smaller than the second threshold value GCth2 (Yes in S151),then the posture control unit 130 causes the right actuator 51 to rotatein the reverse direction, to move the pressure-receiving member 40 fromthe advanced position or the intermediate position to the initialposition (S152). When the motion to the initial position is completed(Yes in S153), then the posture control unit 130 resets the first flagFL1 and the second flag FL2 to 0 (S154), and brings the current controlcycle to an end.

It is to be understood that when the car turns right (herein, thelateral acceleration GC is assumed to be negative), the positive ornegative (plus or minus) sign represented as well as the left or rightactuator 51 used is opposite to those represented or used when the carturns left as described above. To be more specific, in step S121, ifGC≤−GCth1, then it is understood that the magnitude of the lateralacceleration GC is equal to or greater than the first threshold valueGCth1, while if not GC≤−GCth1, then it is understood that the magnitudeof the lateral acceleration GC is not equal to or greater than the firstthreshold value GCth1. Also, in step S151, if GC≥−GCth2, then it isunderstood that the magnitude of the lateral acceleration GC is equal toor smaller than the second threshold value GCth2, while if notGC≥−GCth2, then it is understood that the magnitude of the lateralacceleration GC is not equal to or smaller than the second thresholdvalue GCth2. When the car turns right, the left actuator 51 is caused torotate in the normal or reverse direction.

Referring now to the drawings, a description will be given of anoperation and effects of the present embodiment described above.

As shown in FIG. 9, when the car begins to turn, for example, to theleft, from the normal-time state in which the pressure-receiving member40 is in an initial position (see FIG. 4), the lateral acceleration GCas generated toward rightward increases from then (time t1). When themagnitude of the lateral acceleration GC has become equal to or greaterthan the first threshold value GCth1 (time t2), the controller 100starts a seat posture control under which the right actuator 51 iscaused to rotate in the normal direction, and the right end portion ofthe pressure-receiving member 40 is caused to move from the initialposition to the advanced position (see FIG. 5(b)) for a period (time t2through time t3), to cause the support surface S23 of the seat back S2to orient toward the left that is a turning direction. Accordingly, agood hold of the occupant can be kept during the turning of the car.

Thereafter, when the execution time TE of the seat posture control hasbecome equal to or greater than the execution time threshold value TEth(time t4), the controller 100 causes the right actuator 51 to rotate inthe reverse direction, and causes the right end portion of thepressure-receiving member 40 to move from the advanced position to theintermediate position (see FIG. 5(a)) for a period (time t4 through timet5), to reversely change the orientation of the support surface S23 ofthe seat back S2. With this operation, even if the time for turning ofthe car becomes longer, the state of the seat configurationsignificantly different from that exhibited in the normal time isprevented from continuing, so that the occupant can be made less likelyto feel uncomfortable.

In the present embodiment, when the pressure-receiving member 40 ismoved from the advanced position shown in FIG. 5(b) to the intermediateposition shown in FIG. 5(a) so as to reversely change the orientation ofthe support surface S23 of the seat back S2, the gap D2 formed betweenthe central portion S21 and the right side portion S22 of the seat backS2 becomes greater than the gap D3 formed therebetween when thepressure-receiving member 40 is in the advanced position (i.e., the gapgetting restored), so that the upper body of an occupant can besupported adequately in this gap D2. Accordingly, the stability of theupper body of the occupant during the turning (during the seat posturecontrol) can be improved.

In the present embodiment, as the intermediate position is between theinitial position and the advanced position, the occupant can be madeless likely to feel uncomfortable with a good hold of the occupant beingkept during the turning of the vehicle, in comparison with analternative configuration in which when the execution time TE of theseat posture control is elapsed for a long time, the pressure-receivingmember is moved from the advanced position to the initial position toreversely change the orientation of the seat back.

Referring back to FIG. 9, as the car is getting shifted from the turningstate toward the straight-traveling state, the lateral acceleration GCdecreases accordingly. When the magnitude of the lateral acceleration GChas become equal to or smaller than the second threshold value GCth2(time t6), the controller 100 causes the right actuator 51 to rotate inthe reverse direction, to cause the right end portion of thepressure-receiving member 40 to move from the intermediate position tothe initial position for a period (time t6 through time t7), and causesthe support surface S23 of the seat back S2 to orient frontward, therebybringing the seat posture control to an end.

Although the time for which the actuator 51 is caused to move thepressure-receiving member 40 (i.e. rotation speed of the stepping motorMA) may be set appropriately in accordance with the characteristics ofthe car or the like, the motion from the advanced position to theintermediate position may preferably be produced with a longer period oftime expended therefor, i.e., with a slower speed, than the motion fromthe initial position to the advanced position (motion produced duringstartup of the seat posture control), or the motion from the advanced orintermediate position to the initial position (motion produced during aprocess of bringing the seat posture control to an end). To be morespecific, the motion during startup of the seat posture control orduring the process for bringing the seat posture control to an end maypreferably be produced in such a manner that the orientation of thepressure-receiving member 40 is changed swiftly, while the motion fromthe advanced position to the intermediate position may preferably beproduced in such a manner that the orientation of the pressure-receivingmember 40 is changed gradually.

Second Embodiment

Hereafter, a second embodiment of the present invention will bedescribed in detail with reference made to the drawings whereappropriate. In the following description, for the same components asthose of the previously described embodiment, the same referencecharacters as used in the previously described embodiment are assigned,and a description thereof will be omitted.

Among vehicle seats for use in an automobile or the like, disclosed inJP 2013-199159 A is one which comprises left and right side frames, apressure-receiving member disposed between the left and right sideframes, and rocking mechanisms disposed at left and right sides of thepressure-receiving member. The rocking mechanisms each include anactuator and a link member, and are configured such that the actuatordriven causes the link member to pivot and causes the left end portionor the right end portion of the pressure-receiving member to swingfrontward and rearward. In this technical scheme, the link member isdisposed in contact with the pressure-receiving member, so that a loadapplied from an occupant to the pressure-receiving member can bereceived adequately by the link member.

There is apprehension that the contact of the link member with thepressure-receiving member would possibly cause wear of the link memberand the pressure-receiving member, and the load applied from thepressure-receiving member to the link member would possibly encumber themotion of the link member.

With this in view, it is an object of the present embodiment to providea vehicle seat in which wear of the members can be reduced and the linkmember can be operated smoothly.

It is another object to improve the stability of an occupant.

It is still another object to improve ride comfort as well as to absorbshock.

As shown in FIG. 1, a vehicle seat according to the present embodimentis configured as a car seat S for use in a driver's seat of anautomobile, or the like, and mainly comprises a seat cushion S1, a seatback S2, and a headrest S3.

The seat cushion S1 and the seat back S2 incorporate a seat frame F asshown in FIG. 2. The seat frame F is composed mainly of a seat cushionframe F1 and a seat back frame F2.

The seat back frame F2 is configured to mainly include an upper frame10, left and right side frames 20 that constitute left and right framesof the seat back S2, and a lower frame 30.

The upper frame 10 is comprised of a pipe material bent in asubstantially U-shaped configuration, and includes a lateral pipeportion 11 extending in a lateral direction, on which support brackets12 for use in attaching the headrest S3 thereto are fixed by welding.The upper frame 10 further includes left and right vertical pipeportions 13 extending in an upward-downward direction; the left andright vertical pipe portions 13 and left and right side frame main bodyportions 21 (joined to the lower portions of the left and right verticalpipe portions 13) are respectively welded or otherwise joined togetherin one piece to constitute the left and right side frames 20.

The left and right side frame main body portions 21 are disposedopposite to each other in the lateral direction. Each of the side framemain body portions 21 is formed by sheet-metal stamping process or thelike to have a substantially U-shaped configuration in cross section(having a pair of front and rear bent portions 21A formed by bendingfront and rear end portions in laterally inner directions, the front andrear end portions being located adjacent to two opposite ends facing inthe front and rear directions that are parallel to a direction of ashorter dimension of the side frame main body portions 21). Each of theside frame main body portions 21 is formed to include an upper portionconfigured to envelop and hold the corresponding vertical pipe portion13 and joined to the vertical pipe portion 13, and a lower portionprovided with a bulging portion 22 jutting frontward farther than theupper portion.

A pressure-receiving member 40 and a pair of left and right posturecontrol mechanisms 50 (actuator mechanisms) are disposed between theleft and right side frames 20. The car seat S includes a controller 100(see FIG. 10) for exercising control over the posture control mechanisms50; the controller 100 may be disposed inside or outside of the car seatS.

The pressure-receiving member 40 is a plate member configured to receivea load from an occupant seated on the car seat S through an outercovering and a cushiony material, and is formed of plastic or the likewith elastically deformable property. The pressure-receiving member 40includes a pressure-receiving portion 41 and left and right supportportions 42 formed integrally in one piece, of which thepressure-receiving portion 41 is disposed in a laterally centralposition to face the back of the occupant, and the support portions 42protruding from upper portions of left and right ends of thepressure-receiving portion 41 laterally outward and frontward (inobliquely-laterally-outward-and-frontward directions).

The pressure-receiving member 40 is connected to the left and right sideframes 20 via an upper connecting wire W1 and a lower connecting wire W2in such a manner that the pressure-receiving member 40 is movablefrontward and rearward relative to the left and right side frames 20.The upper connecting wire W1 as a connecting wire has its both endsconnected to the posture control mechanisms 50 fixed to the side frames20, respectively, so that the upper connecting wire W1 runs between theleft and right side frames 20. The upper connecting wire W1 is disposedalong an upper region of a back surface of the pressure-receiving member40 and held by engagement of engageable claws (not shown) formed at theupper region of the rear surface of the pressure-receiving member 40with the upper connecting wire W1, to thereby establish connectionbetween the upper region of the pressure-receiving member 40 and theleft and right side frames 20. The lower connecting wire W2 has its bothends connected to wire mount portions 23 (only one illustrated) providedon the side frames 20, respectively, so that the lower connecting wireW2 runs between the left and right side frames 20. The lower connectingwire W2 is disposed along a lower region of the back surface of thepressure-receiving member 40 and held by engagement of engageable claws(not shown) formed at the lower region of the rear surface of thepressure-receiving member 40 with the lower connecting wire W2, tothereby establish connection between the lower region of thepressure-receiving member 40 and the left and right side frames 20.

The posture control mechanism 50, which is a mechanism for causing thepressure-receiving member 40 to move, is provided on each of the leftand right side frames 20, and thus disposed at the left and right sidesof the pressure-receiving member 40. Although a detailed descriptionwill be given later, the posture control mechanism 50 is configured tocause the left end portion or the right end portion of thepressure-receiving member 40 to move from an initial position shown inFIG. 12(a) frontward to an advanced position shown in FIG. 12(c) tothereby cause the pressure-receiving member 40 to orient to the right orto the left, or to move (reverse) from the advanced position to theinitial position.

As shown in FIG. 10, the posture control mechanism 50 is configured tomainly include a linkage 50A connected via the upper connecting wire W1to the pressure-receiving member 40, and an actuator 51 (source ofdriving power) for actuating the linkage 50A. As the upper connectingwire W1 and the left and right posture control mechanisms 50 areconstructed substantially in a laterally symmetric configuration, thefollowing description will be elaborated mainly with reference to theillustration of the configuration of the left-side mechanisms.

The actuator 51 mainly includes a stepping motor 51A (motor) configuredto be capable of rotating in the normal direction and in the reversedirection, a gear box 51B including a train of gears (not shown) forreducing the speed with which the driving power from the stepping motor51A is transmitted, and an output shaft 51C to which the driving powerfrom the stepping motor 51A is transmitted with the reduced speed. Theactuator 51 is fixed to the side frame 20 via a retaining bracket 52(52A, 52B).

As shown in FIG. 11, the linkage 50A is provided pivotally relative tothe side frame 20, and mainly includes two links for causing thepressure-receiving member 40 to move, specifically: a first link member300, and a second link member 200 (as a link member). The second linkmember 200 is configured as a plate member made of stamped or otherwiseformed sheet metal.

The first link member 300 mainly has a shaft hole 310 provided at oneend portion thereof, a pin hole 320 provided at another end portion, andstopper portions 330. The first link member 300 is connected to theoutput shaft 51C of the actuator 51 by serration fitting the shaft hole310 on the output shaft 51C of the actuator 51, and retained by ane-style retaining ring 56 (see FIG. 10) so as not to disconnect from theoutput shaft 51C. Accordingly, the first link member 300 is configuredto swing substantially in a frontward or rearward direction when theactuator 51 is driven to rotate the output shaft 51C. The stopperportions 330 are portions restricting a swinging motion of the firstlink member 300 itself when contacting a fixed stopper member 70provided on the retaining bracket 52A. To be more specific, the stopperportions 330 include a first stopper portion 331 protruding from aposition at or near a center of a main body portion 301 of the firstlink member 300 substantially in a frontward direction, and a secondstopper portion 332 protruding from a position at or near the center ofthe main body portion 301 of the first link member 300 substantially ina leftward direction. The first link member 300 is restricted in itsfrontward swinging motion when the first stopper portion 331 comes incontact with the fixed stopper member 70, and is restricted in itsrearward swinging motion when the second stopper portion 332 comes incontact with the fixed stopper member 70.

The second link member 200 mainly comprises a stopper 210 and a pin hole220 provided at one end portion thereof, and a through hole 240 providedat another end portion thereof. The second link member 200 is providedin a manner swingable substantially in a frontward or rearward directionrelative to the first link member 300 on a pin 54A engaged in its pinhole 220 and the pin hole 320 of the first link member 300. The stopper210 is a portion restricting a rearward swinging motion of the secondlink member 200 when contacting a side surface 302 of the first linkmember 300 (see FIG. 12(c)). The stopper 210 which protrudes from theone end portion of the second link member 200 is bent at a farthest endof its protruded portion and extends therefrom to a lower side on whichthe first link member 300 is disposed (see also FIG. 10).

As shown in FIGS. 10 and 11, a torsion spring 55 is disposed in amechanistically interjacent position between the first link member 300and the second link member 200. The torsion spring 55 is a member whichbiases the second link member 200 toward a direction (indicated by arrowin FIG. 11) in which the second link member 200 is caused thereby toswing frontward, and includes a coiled portion 55A, a substantiallyL-shaped first arm portion 55B extending from an upper end of the coiledportion 55A radially outward and having a distal end portion thereofextending downward, and an L-shaped second arm portion 55C extendingfrom a lower end of the coiled portion 55A radially outward and having adistal end portion thereof extending downward. The coiled portion 55A ofthe torsion spring 55 is engaged with the pin 54A, the first arm portion55B that is one end of the torsion spring 55 is hooked on the firststopper portion 331 of the first link member 300, and the second armportion 55C that is another end of the torsion spring 55 is hooked onthe stopper 210 of the second link member 200.

As shown in FIG. 11, the support portion 42 of the pressure-receivingmember 40 includes a first support portion 42A and a second supportportion 42B. The first support portion 42A is a portion extending froman end of the pressure-receiving portion 41, and extends substantiallystraight in an obliquely laterally-outward-and-frontward direction fromthe end of the pressure-receiving portion 41 as viewed from above orfrom below. The second support portion 42B is a portion extending from afront end of the first support portion 42A, at which the support portionis bent, so that the second support portion 42B extends in a directionbiased slightly frontward relative to a direction of extension of thefirst support portion 42A, and the second support portion 42B extends inan obliquely laterally-outward-and-frontward direction while being socurved as to bulge frontward as viewed from above or from below.

The upper connecting wire W1 includes a wire central portion W11disposed along the back surface of the pressure-receiving portion 41,and a pair of left and right wire side portions W12 (only oneillustrated) extending from the left and right ends of the wire centralportion W11 in obliquely laterally-outward-and-frontward directions anddisposed along the back surface of the support portions 42. The wireside portion W12 includes a first portion W31, a second portion W32, anda third portion W33; the upper connecting wire W1 includes bent portionsW13 provided at left and right end portions, more specifically, each ata junction of the second portion W32 and the third portion W33. Thefirst portion W31 is a portion extending from an end of the wire centralportion W11, and extends in such a direction as to extend along the backsurface of the first support portion 42A. The second portion W32 is aportion extending from a front end of the first portion W31, at whichthe wire side portion is bent, so that the second portion W32 extends ina direction biased slightly frontward relative to a direction ofextension of the first portion W31, and the second portion W32 extendsin an obliquely laterally-outward-and-frontward direction. The bentportion W13 is a portion shaped substantially like a letter V in planview by bending, so as to extend from the second portion W32 in adirection away from the support portion 42, specifically, in anobliquely laterally-outward-and-rearward direction. The third portionW33 extends in an obliquely laterally-outward-and-rearward direction. Adistal end portion of the third portion W33 is bent downward to have asubstantially L-shaped configuration, to provide an end portion W14engaged in the through hole 240 of the second link member 200. In thisway, the upper connecting wire W1 is connected to the second link member200, and connects the pressure-receiving member 40 engaged with the wirecentral portion W11 to the left and right second link members 200.

The bent portion W13 is located rearward of the support portion 42 whilefacing the back surface of the support portion 42. The bent portion W13is located at a distance from the support portion 42 when no rearwardload from an occupant is applied to the pressure-receiving member 40 orany load applied rearward from an occupant to the pressure-receivingmember 40 is less than a predetermined magnitude. When a rearward loadnot less than the predetermined magnitude is applied from an occupant tothe pressure-receiving member 40 and causes the support portion 42 toyield rearward, as shown in FIG. 12 (c), the back surface of the supportportion 42 comes in contact with the bent portion W13 from frontward. Inother words, from the viewpoint of the bent portion W13, when a rearwardload not less than the predetermined magnitude is applied from anoccupant to the pressure-receiving member 40 and causes the supportportion 42 to yield, the bent portion W13 comes in contact with thesupport portion 42 from rearward. It is to be understood that a loadrequired for contact of the bent portion W13 and the support portion 42can be adjusted by appropriately setting a gap made between the bentportion W13 and the support portion 42 when no load is applied to thepressure-receiving member 40 and/or flexibility of thepressure-receiving member 40 and/or the cushiony material of the seatback S2.

As shown in FIG. 11, the second link member 200 is located rearward ofthe support portion 42 while facing the back surface of the supportportion 42. The second link member 200 is located in a position oppositeto the support portion 42 such that the first member W31 and the secondmember W32 of the wire side portion W12 are sandwiched by the secondlink member 200 and the support portion 42 as viewed from above or frombelow; thus, the second link member 200 is so arranged as not to come incontact with the support portion 42.

The second portion W32 that is a part of the upper connecting wire W1 isdisposed between the second link member 200 and the support portion 42as viewed from above or from below (i.e., a direction of an axis of theswinging motion of the second link member 200). Also, the second portionW32 is disposed between the pin 54A (the axis of the swinging motion ofthe second link member 200) and the support portion 42 as viewed fromabove or from below.

The left and right posture control mechanisms 50 are configured to beindependently actuated by the actuator 51 under control of thecontroller 100 (see FIG. 10), to cause the pressure-receiving member 40inside the seat back S2 to orient toward a turning direction (see FIG.13(c)). Among feasible methods of control exercised by the controller100 are methods of various types, which include, for example, a methodcomprising computing a lateral acceleration and a turning directionbased upon signals from a wheel velocity sensor and a steering anglesensor, and when the thus-computed lateral acceleration has becomegreater than a predetermined threshold value, causing the actuator 51(stepping motor 51A) of the posture control mechanism 50 located on aturning-direction outer side to be activated, thereby causing thepressure-receiving member 40 to orient toward the turning direction.

A description will be given of the motion of the car seat S duringturning of the car.

When the car turns right, the controller 100 activates the actuator 51of the left posture control mechanism 50. Thus, from the state shown inFIG. 12(a), the actuation proceeds as shown in FIGS. 12(b), (c); i.e.,the first link member 300 swings frontward, and the second link member200 moves frontward while swinging relative to the first link member300. Accordingly, the left end portion of the upper connecting wire W1moves frontward, and causes the left support portion 42 (left endportion) of the pressure-receiving member 40 to move from the initialposition to the advanced position located in front thereof. As a result,as shown in FIGS. 13(a)-(c), the pressure-receiving member 40, as awhole, orients to the right that is the turning direction, so that thecentrifugal force imposed on an occupant during the turning canadequately be supported by the seat back S2. When the left end portionof the pressure-receiving member 40 moves from the initial positiontoward the advanced position, the second link member 200 being actuatedis kept out of contact with the pressure-receiving member 40. The bentportion W13 of the upper connecting wire W1 comes in contact with thesupport portion 42 from rearward as shown in FIGS. 12(a)-(c), as thecentrifugal force applied to an occupant during turning produces arearward load equal to or greater than a predetermined magnitude fromthe occupant which in turn causes the left support portion 42 to yield,thus deforming rearward. At this time, the bent portion W13 comes incontact from rearward with a portion of the pressure-receiving member 40on or near the left edge thereof, to be more specific, with a laterallyouter end portion of the left support portion 42 located in the advancedposition.

When the car is getting shifted from the turning state toward thestraight-traveling state, the controller 100 causes the actuator 51 ofthe left posture control mechanism 50 to be driven in a directionreverse to the direction in which it is driven at the time of turning.Thus, from the state shown in FIG. 12(c), the actuation proceeds asshown in FIGS. 12(b), (a); i.e., the first link member 300 swingsrearward. Then, a load applied from an occupant to thepressure-receiving member 40 causes the second link member 200 to moverearward while swinging relative to the first link member 300.Accordingly, the left end portion of the upper connecting wire W1 movesrearward, and causes the left end portion of the pressure-receivingmember 40 to move from the advanced position to the initial position. Asa result, the pressure-receiving member 40 is shifted from therightward-orienting state shown in FIG. 13(c) back to thefrontward-orienting state shown in FIG. 13(a). When the left end portionof the pressure-receiving member 40 moves from the advanced positiontoward the initial position, as well, the second link member 200 beingactuated is kept out of contact with the pressure-receiving member 40.

When the car turns left, the controller 100 activates the actuator 51 ofthe right posture control mechanism 50. Subsequent motions of thepressure-receiving member 40 and the right posture control mechanism 50are similar to those imparted during the right turning; thus, a detaileddescription will be omitted.

According to the present embodiment as described above, the second linkmember 200 is to kept out of contact with the support portion 42;therefore, wear of the second link member 200 and/or thepressure-receiving member 40 (in particular, pressure-receiving member40 made of plastic) can be suppressed. Furthermore, as the second linkmember 200 is kept out of contact with the support portion 42, no directload from the pressure-receiving member 40 is imposed on the second linkmember 200; therefore, the second link member 200 (posture controlmechanism 50) can be operated adequately.

When a rearward load of a predetermined magnitude or greater appliedfrom an occupant to the pressure-receiving member 40 causes the supportportion 42 to become deformed, the bent portion W13 of the upperconnecting wire W13 comes in contact with the support portion 42 fromrearward; therefore, the support portion 42 of the pressure-receivingmember 40 receiving the load from the occupant can be supported by thebent portion W13 (upper connecting wire W1). Accordingly, the stabilityof the occupant seated on the car seat S can be improved. Moreover, withthe help of the springiness of the upper connecting wire W1, the loadfrom the occupant can be received softly, so that improved ride comfortof the occupant and shock absorption can be achieved.

Furthermore, with consideration given to a large load imposed on thesupport portion 42 in the advanced position from the occupant by thecentrifugal force applied to the occupant during turning, the bentportion W13 is so located as to be able to come in contact from rearwardwith the laterally outer end portion of the support portion 42 in theadvanced position, as shown in FIG. 12(c); therefore, when the bentportion W13 comes in contact with the laterally outer end portion of thesupport portion 42, the laterally outer end portion of the supportportion 42 (the portion on or near the laterally outer edge of thesupport portion 42) can be supported by the upper connecting wire W1.With this configuration, the stability of the occupant can be improved.

Third Embodiment

Hereafter, a third embodiment of the present invention will be describedin detail with reference made to the drawings where appropriate.

As shown in FIG. 14, in the present embodiment, the upper connectingwire W1 includes a wire central portion W11 and a pair of left and rightwire side portions W12 (only one illustrated). The wire side portion W12includes a first portion W31, a second portion W34, and a third portionW35; the upper connecting wire W1 includes bent portions W16 provided atleft and right end portions, more specifically, each at a junction ofthe second portion W34 and the third portion W35. The second portion W34extends from a front end of the first portion W31, at which the wireside portion is bent, so that the second portion W34 extends in adirection biased slightly frontward relative to a direction of extensionof the first portion W31, and the second portion W34 further extends inan obliquely laterally-outward-and-frontward direction long up to aposition close to the front end of the second support portion 42B. Thebent portion W16 is a portion shaped substantially like a letter U inplan view by bending, so as to extend from the second portion W34 in adirection away from the support portion 42, specifically, in asubstantially rearward direction. The third portion W35 extends in asubstantially rearward direction, and includes a distal end portion W14bent downward and engaged in the through hole 240 of the second linkmember 200.

The bent portion W16 is located rearward of the support portion 42 whilefacing the back surface of the support portion 42. In the presentembodiment, the bent portion W16 is so disposed as to always be kept incontact with the support portion 42 from rearward during movement of thesupport portion 42 between the initial position and the advancedposition, in other words, regardless of the position of the supportportion 42. That is, the bent portion W16 is disposed in such a mannerthat the support portion 42, regardless of its position, can always besupported thereby from rearward.

The second link member 200 is located rearward of the support portion 42while facing the back surface of the support portion 42. The second linkmember 200 is located in a position opposite to the support portion 42such that the first member W31 and the second member W34 of the wireside portion W12 are sandwiched by the second link member 200 and thesupport portion 42 as viewed from above or from below; thus the secondlink member 200 is so arranged as not to come in contact with thesupport portion 42.

The second portion W34 that is a part of the upper connecting wire W1 isdisposed between the second link member 200 and the support portion 42as viewed from above or from below. Also, the second portion W34 isdisposed between the pin 54A (the shaft on which the second link member200 may swing) and the support portion 42 as viewed from above or frombelow.

A brief description will now be given of the motion of the car seat Sduring turning of the car according to the present embodiment, takingthe right-turn situation as an example.

When the car turns right, the actuator 51 of the left posture controlmechanism 50 is activated. Thus, from the state shown in FIG. 15(a), theactuation proceeds as shown in FIGS. 15(b), (c); i.e., the first linkmember 300 swings frontward, and the second link member 200 movesfrontward while swinging relative to the first link member 300.Accordingly, the left end portion of the upper connecting wire W1 movesfrontward, and causes the left support portion 42 (left end portion) ofthe pressure-receiving member 40 to move from the initial position tothe advanced position located in front thereof. In this process, thesecond link member 200 is actuated while being kept out of contact withthe pressure-receiving member 40. Furthermore, as shown in FIG. 15(c),the bent portion W16 of the upper connecting wire W1 comes in contactwith the laterally outer end portion of the left support portion 42 inthe advanced position from rearward. If a greater load is imposed on thesupport portion 42, then the wire side portion W12 of the upperconnecting wire W1 undergoes elastic deformation to get outstretchedlaterally outward, and the second link member 200 thus pushed by theupper connecting wire W1 swings counterclockwise as seen in the drawing,so that the bent portion W16 deforms and opens out; however, that loadcan be received in a shock-absorbing manner by using the elasticity ofthe bent portion W16.

When the car is getting shifted from the turning state back toward thestraight-traveling state, the actuator 51 of the left posture controlmechanism 50 is driven in a direction reverse to the direction in whichit is driven at the time of turning. Thus, from the state shown in FIG.15(c), the actuation proceeds as shown in FIGS. 15(b), (a); i.e., thefirst link member 300 swings rearward. Then, a load applied from anoccupant to the pressure-receiving member 40 causes the second linkmember 200 to move rearward while swinging relative to the first linkmember 300. Accordingly, the left end portion of the upper connectingwire W1 moves rearward, and causes the left end portion of thepressure-receiving member 40 to move from the advanced position to theinitial position. In this process as well, the second link member 200 isactuated while being kept out of contact with the pressure-receivingmember 40.

According to the present embodiment as described above, as in the secondembodiment, the second link member 200 is kept out of contact with thesupport portion 42; therefore, wear of the pressure-receiving member 40or the like can be suppressed. Furthermore, as no direct load from thepressure-receiving member 40 is imposed on the second link member 200,the second link member 200 can be operated adequately.

Moreover, since the bent portion W16 comes in contact with the laterallyouter end portion of the support portion 42 located in the advancedposition from rearward, the portion of the support portion 42 on or nearthe laterally outer edge thereof can be supported by the upperconnecting wire W1, so that the stability of the occupant can beimproved.

Furthermore, according to the present embodiment in which the bentportion W16 of the upper connecting wire W1 is always in contact withthe support portion 42 from rearward, the support portion 42 of thepressure-receiving member 40 which receives a load from the occupant canbe supported constantly by the upper connecting wire W1. Accordingly,the stability of the occupant can be improved. Furthermore, since theload from the occupant can be received softly by making use of thespringiness of the upper connecting wire W1, the improved ride comfortand shock absorption can be achieved.

Fourth Embodiment

Hereafter, a fourth embodiment of the present invention will bedescribed in detail with reference made to the drawings whereappropriate. In describing the present embodiment, “laterally inner side(laterally inward)” and “laterally outer side (laterally outward)” areintended to refer to the laterally inner side (inward) and outer side(outward) with respect to the vehicle seat, unless otherwise specified.

A vehicle seat to be installed in an automobile or the like comprisesleft and right side frames. For example, a seat apparatus disclosed inJP 2013-49356 A is configured such that a frame of the seat backincludes a pair of left and right side frames extending inupward-downward direction. The seat apparatus disclosed in JP 2013-49356A further comprises a back plate disposed between the left and rightside frames and a rocking mechanism configured to rock the back plate,wherein the orientation of the back plate can be changed to the left orto the right through actuation of the rocking mechanism.

In recent years, vehicle seats are provided with many devices such asthe aforementioned rocking mechanism, and therefore, effective use ofavailable spaces stands in need.

With this in view, it is an object of the present embodiment to providea vehicle seat in which effective use of available spaces can beachieved.

It is another object to protect a device(s) provided in a vehicle seat.

It is still another object to provide a simplified structure formounting a device(s).

It is still another object to check increase in size of a vehicle seatand to provide greater rigidity in side frames.

It is still another object to make devices properly operable.

In the present embodiment, a seat back S2 incorporates a seat back frameF2 as shown in FIG. 16.

The seat back frame F2 mainly includes an upper frame 10, and left andright side frames 20 that constitute left and right frames of the seatback S2. The upper frame 10 is formed of a metal pipe material bent in asubstantially U-shaped configuration, and has lower portions thereofwelded or otherwise joined integrally to upper portions of the left andright side frames 20. A detailed description of the side frames 20 willbe given later.

A pressure-receiving member 40 as a movable part of the seat back S2 (ofa car seat S) and a pair of left and right posture control mechanisms 50(actuator mechanisms) are disposed between the left and right sideframes 20. An airbag device 60 as a second device is provided on theright side frame 20 that is disposed at a laterally outer side of thecar.

The pressure-receiving member 40 is a plate member configured to receivea load from an occupant seated on the car seat S through an outercovering and a cushiony material, and is formed of plastic or the likewith elastically deformable property. The pressure-receiving member 40is configured to include a pressure-receiving portion 41 and left andright support portions 42 formed integrally in one piece, of which thepressure-receiving portion 41 is disposed to face the back of theoccupant, and the support portions 42 protrudes from upper portions ofleft and right ends of the pressure-receiving portion 41 inobliquely-laterally-outward-and-frontward directions.

The pressure-receiving member 40 is connected to the left and right sideframes 20 through an upper connecting wire W1 and a lower connectingwire W2 in such a manner that the pressure-receiving member 40 ismovable frontward and rearward relative to the left and right sideframes 20. The upper connecting wire W1 has two end portions connectedto the posture control mechanisms 50 fixed to the side frames 20,respectively, and configured to connect the upper portion of thepressure-receiving member 40 to the left and right side frames 20 byengagement of engageable claws (not shown) formed at the upper region ofthe rear surface of the pressure-receiving member 40 with the upperconnecting wire W1. The lower connecting wire W2 has its both endportions connected to wire mount portions (not shown) provided on theside frames 20, respectively, and configured to connect the lowerportion of the pressure-receiving member 40 to the left and right sideframes 20 by engagement of engageable claws (not shown) formed at thelower region of the rear surface of the pressure-receiving member 40with the lower connecting wire W2.

The posture control mechanism 50, which is a mechanism for causing thepressure-receiving member 40 to move, is provided on each of the leftand right side frames 20, and thus disposed at the left and right sidesof the pressure-receiving member 40. The posture control mechanism 50 isconfigured: to cause the left end portion or the right end portion ofthe pressure-receiving member 40 to move from an initial position (seeFIG. 4) to an advanced position (see FIG. 5(b)) to thereby cause thepressure-receiving member 40 to orient to the right or to the left; orto move (reverse) from the advanced position to the initial position. Tothis end, the posture control mechanism 50 mainly includes a linkage 50A(first link member 53 and second link member 54) connected via the upperconnecting wire W1 to the pressure-receiving member 40, and an actuator51 as a first device configured to actuate the linkage 50A to cause thepressure-receiving member 40 to move.

The actuator 51 is attached to a laterally inner side of the side frame20 (side portion 421) via a retaining bracket (not shown) by tighteningbolts 491 and nuts 492 (see FIG. 17).

The airbag device 60 is configured to include a bag (not shown) and aninflator or other components. The airbag device 60 may be of a knownconfiguration, and thus a detailed description thereof is omittedherein. The airbag device 60 is attached to a laterally outer side ofthe right side frame 20 (side portion 421) by tightening bolts 493 andnuts 494 (see FIG. 17).

Each of the left and right side frames 20, which includes a side portion421, a pair of front and rear inner extension portions 422, and a pairof front and rear outer extension portions 423, is formed to have ashape of a seriffed letter I (or a letter H without serifs) in crosssection (see also FIG. 18). In the present embodiment, as the left andright side frames 20 are provided with a configuration laterallysymmetric to each other, the following description will be elaboratedmainly with reference to the illustration of the configuration at theright side frame.

As shown in FIG. 17, the side portion 421 is a portion to which theactuator 51 and the airbag device 60 are attached, and has a shape of aplate elongated in an upward-downward direction. The side portion 421includes an upper side portion 421A as a first portion, a lower sideportion 421B as a second portion that is formed below the upper sideportion 421A, and a connecting portion 421C. The actuator 51 is attachedto the laterally inner side of the upper side portion 421A, and theairbag device 60 is attached to the laterally outer side of the lowerside portion 421B. Accordingly, the actuator 51 and the airbag device 60are disposed in positions shifted from each other in the upward-downwarddirection. The lower side portion 421B is disposed in a position shiftedfrom the upper side portion 421A in the laterally inner direction, andthe connecting portion 421C extends from a lower end of the upper sideportion 421A to an upper end of the lower side portion 421B which ispositioned below the lower end of the upper side portion 421A off to thelaterally inner side, such that the connecting portion 421C connects thelower end of the upper side portion 421A and the upper end of the lowerside portion 421B. With this configuration, the actuator 51 and theairbag device 60 are located to overlap each other partly when viewedfrom above or from below, to be more specific, a laterally outer endportion of the actuator 51 and a laterally inner end portion of theairbag device 60 overlap each other.

As shown in FIGS. 18(a), (b), the inner extension portions 422 areportions extending from the respective front and rear ends (edges) ofthe side portion 421 laterally inward. The actuator 51 is disposed in arecess 424 formed by the side portion 421 and the front and rear innerextension portions 422.

The outer extension portions 423 are portions extending from therespective front and rear ends (edges) of the side portion 421 laterallyoutward. The airbag device 60 is disposed in a recess 425 formed by theside portion 421 and the front and rear outer extension portions 423.

The side frame 20 as described above may be formed, as an example, oftwo metal sheets welded or otherwise joined together in one piece. To bemore specific, one metal sheet to constitute the side portion 421 isbent to form the upper side portion 421A, the connecting portion 421Cand the lower side portion 421B. Thereafter, another elongate metalsheet to constitute the extension portions 422, 423 is disposed to wraparound the edge of the one metal sheet (side portion 421) and welded orotherwise joined thereto in one piece. In this way, the side frame 20can be formed.

According to the present embodiment as described above, in which theactuator 51 is disposed in the recess 424 formed by the side portion 421and the inner extension portions 422 of the side frame 20, the space inthe seat back S2 can be utilized effectively. Moreover, the actuator 51can be protected by the inner extension portions 422 disposed in frontand in the rear of the actuator 51.

Furthermore, since the airbag device 60 is disposed in the recess 425formed by the side portion 421 and the outer extension portions 423, thespace in the seat back S2 can be utilized more effectively. Moreover,the airbag device 60 can be protected by the outer extension portions423 disposed in front and in the rear of the airbag device 60.

Furthermore, since the actuator 51 and the airbag device 60 are locatedin positions shifted from each other in the upward-downward direction,the bolts/nuts 491/492 and the bolts/nuts 493/494 are rendered unlikelyto interfere with each other. Moreover, the bolts/nuts 491/492 and theairbag device 60 are rendered unlikely to interfere with each other,whereas the bolts/nuts 493/494 and the actuator 51 are rendered unlikelyto interfere with each other. Moreover, the actuator 51 and the airbagdevice 60 can be attached easily at laterally opposite sides bytightening the bolts 491, 493 and the nuts 492, 494. In other words,since the actuator 51 and the airbag device 60 are located in positionsshifted from each other in the upward-downward direction, the structuresfor mounting the actuator 51 and the airbag device 60 can be embodied ina simple structure.

Furthermore, since the lower side portion 421B to which the airbagdevice 60 is attached is in a position shifted laterally inward fromthat of the upper side portion 421A to which the actuator 51 isattached, available space can be utilized effectively and the increasein size (particularly lateral dimension) of the car seat S as wouldresult from arrangement of the airbag device 60 at the laterally outerside of the side frame 20 can be checked. Moreover, as compared with analternative configuration in which the side portion is an unbent, flatplate, greater rigidity can be provided in the side frame 20. To be morespecific, since the side portion 421 includes an upper side portion421A, a lower portion 421B located in a position shifted from that ofthe upper side portion 421A, and a connecting portion 421C connectingthe upper side portion 421A and the lower side portion 421B, which areprovided integrally in one piece, the increase in the rigidity of theside portion 421 in itself may be increased, and in particular theextension portions 422, 423 provided at the edge of the side portion 421can be enhanced in rigidity. In addition, the extension portions 422,423 (metal sheets of which the extension portions 422, 423 are made) canbe enhanced in structure against torsion.

Furthermore, since the airbag device 60 as the second device is disposedat a laterally outer side of the side frame 20, the bag (not shown) ofthe airbag device 60 can be supported by the side portion 421 when thebag inflates, so that the bag can be deployed properly. In other words,provision of the airbag device 60 as the second device at the laterallyouter side of the side frame 20 helps proper actuation of the airbagdevice 60.

Although some embodiments of the present invention have been describedabove, the present invention is not limited to the above-describedembodiments. Specific configurations may be modified where appropriatewithout departing the gist of the present invention as will be describedbelow.

In the first embodiment, the lateral acceleration acquisition unit 110is configured to acquire a lateral acceleration GC by computation basedon the wheel velocity and the steering angle, but this is not anessential limitation. For example, the lateral acceleration acquisitionunit may be configured to acquire a lateral acceleration from a lateralacceleration sensor. Alternatively, if an electronic control unitequipped in the car is capable of providing a lateral acceleration, thelateral acceleration acquisition unit may be configured to interrogatethe electronic control unit and acquire the lateral acceleration.

In the first embodiment, the posture control unit 130 is configured suchthat when a magnitude of the lateral acceleration GC has become equal toor greater than the first threshold value GCth1, a seat posture controlis started under which the pressure-receiving member 40 is moved fromthe initial position to the advanced position; however, the condition(s)on which the seat posture control is activated is not limited to thecondition as prescribed in the first embodiment. Neither is thecondition(s) on which the seat posture control is brought to an end. Forexample, the posture control unit may alternatively be configured toexecute the seat posture control based on combination of the steeringangle and the vehicle speed without computing the lateral acceleration.

In the first embodiment, the intermediate position as the secondposition is between the initial position and the advanced position(first position), but is not limited to this position; for example, thesecond position may be the same position as the initial position. Thesecond position may comprise a plurality of positions between theinitial position and the first position. In other words, the posturecontrol unit may be configured to reversely change the orientation ofthe seat back stepwise in accordance with a lapse of the execution timeof the seat posture control. For example, in the case where the firstintermediate position and the second intermediate position are arrangedin this sequence from the front between the initial position and theadvanced position, the posture control unit may be configured such thatthe pressure-receiving member is moved from the advanced position to thefirst intermediate position when the execution time of the seat posturecontrol has become equal to or greater than a first execution timethreshold value, and further moved from the first intermediate positionto the second intermediate position when the execution time of the seatposture control has become equal to or greater than a second executiontime threshold value that is a time longer than the first execution timethreshold value. Also in the case where three or more intermediatepositions are arranged, the control proceeds in a similar manner.

In the above-described embodiments, the posture control mechanism 50(actuator 51) is configured to be capable of changing the orientation ofthe seat back S2 (the orientation of the support surface S23) laterallyby moving the pressure-receiving member 40 as part of the seat back S2,but this is not an essential limitation. For example, the actuator maybe configured to be capable of changing the orientation of the seat back(the orientation of the side portions) laterally by moving the left andright side portions of the seat back (see S22 in FIG. 1) as part of theseat back. Also, the actuator may be configured to be capable ofchanging the orientation of the whole seat back laterally by moving thewhole seat back. Moreover, the actuator may be capable of changing theorientation of the whole car seat laterally by moving the whole carseat. In the above-described embodiments, the pressure-receiving member40 includes the support portions 42 provided to protrude from the upperportions of the left and right ends of the pressure-receiving portion41, but this is not an essential limitation. For example, the supportportions may be provided to protrude from vertically central portions ofthe left and right ends of the pressure-receiving portion, or may beprovided to protrude from the whole lengths of the left and right endsof the pressure-receiving portion.

In the second embodiment, the linkage 50A is of two-link configurationwhich includes the second link member 200 as a link member, but this isnot an essential limitation. For example, the linkage may be configuredto only include the link member (i.e., a single-link configuration), ormay be configured to comprise three or more links that include the linkmember.

In the second embodiment, the upper connecting wire W1 (connecting wire)is arranged such that at least when a rearward load not less than thepredetermined magnitude is applied from an occupant to thepressure-receiving member 40, the bent portion W13 comes in contact withthe support portion 42; however, this is not an essential limitation.For example, the bent portion of the connecting wire may be so arrangedas not to come in contact with the support portion.

In the fourth embodiment, the side portion 421 of the side frame 20includes an upper side portion 421A as a first portion and a lower sideportion 421B as a second portion, but this configuration is not anessential limitation. For example, the second portion may be formedabove the first portion. Alternatively, the first portion and the secondportion may be provided as those arranged in the front-rear direction asviewed from the left or right direction. Also, the side portions of theside frame may be formed as a flat plate without being bent.

In the fourth embodiment, as shown in FIG. 17, the actuator 51 as thefirst device and the airbag device 60 as the second device are arrangedin positions shifted from each other in the upward-downward direction,but this is not an essential limitation. For example, the actuator andthe airbag device may be arranged at the same height so as to overlap asviewed from the left or right direction. With this configuration,additional devices or parts other than the actuator and the airbagdevice can be attached to the side frame; therefore, the available spacecan be utilized more effectively.

In the fourth embodiment, the side frame 20 so formed in one piece ofone metal plate welded or otherwise joined integrally to edges ofanother metal plate as to have a shape of a seriffed letter I (or aletter H without serifs) in cross section is illustrated by way ofexample, but this is not an essential limitation. For example, the sideframe, if designed to have a constant cross sectional shape, may beformed by extrusion of metal material. Alternatively, the side frame maybe so formed as to have a shape of a seriffed letter I in cross sectionwith a side portion, inner extension portions and outer extensionportions, by bending one metal sheet.

In the fourth embodiment, the front and rear inner extension portions422 are configured to have the same lateral length, but this is not anessential limitation; for example, the front and rear inner extensionportions may have lateral lengths different from each other. The sameapplies to the outer extension portions. Similarly, the inner extensionportion and the outer extension portion aligned laterally may have thesame lateral length.

In the fourth embodiment, the inner extension portions 422 and the outerextension portions 423 are all shaped to extend laterally straight, butthis shape is not an essential limitation. For example, the innerextension portions and the outer extension portions may have distal endportions bent inward or outward in the front-rear direction.Alternatively, the inner extension portions and the outer extensionportions may have distal end portions curved inward or outward in thefront-rear direction.

In the fourth embodiment, each of the left and right side frames 20 isso formed as to have a shape of a seriffed letter I in cross sectionwith a side portion 421, inner extension portions 422 and outerextension portions 423, but this is not an essential limitation. Forexample, the first device and/or the second device may be attached toonly one of the left and right side frames, and in this configuration,that only one of the left and right side frames may be so formed as tohave a shape of a seriffed letter I in cross section with a sideportion, inner extension portions and outer extension portions.

In the fourth embodiment, illustrated as an example of the first deviceis the actuator 51 configured to move the movable portion(pressure-receiving member 40) of the seat back S2, while illustrated asan example of the second device is the airbag device 60; however, thisconfiguration is not an essential limitation. For example, the firstdevice may be an actuator configured to move a movable portion of theseat cushion. The car seat may be configured such that both of the firstdevice and the second device are attached to the left and right sideframes, respectively. The car seat may be configured such that the firstdevice is attached to only one of the left and right side frames. Thecar seat may be configured to only include the first device but notinclude the second device.

In the fourth embodiment, the left and right side frames 20 thatconstitute the left and right frames of the seat back S2 are illustratedas an example of the left and right side frames, but this is not anessential limitation. For example, the side frames may be side frames ofa frame that constitutes left and right frames of the seat cushion. Theside frames may be configured to have an integral structure formed ofthe frame of the seat back and the frame of the seat cushion.

In the above-described embodiments, the car seat S for use in anautomobile is illustrated as an example of the vehicle seat, but this isnot an essential limitation; rather, the vehicle seat may include anyother vehicle seats for use, for example, in snowmobiles, railcars,ships, aircrafts, and so forth.

The invention claimed is:
 1. A vehicle seat comprising: a seat cushion;and a seat back, wherein the seat back comprises: left and right sideframes which constitute left and right frames of the seat back; apressure-receiving member disposed between the left and right sideframes to receive a load from an occupant; left and right link memberseach provided swingably relative to a respectively corresponding sideframe, such that a swinging motion of each of the left and right linkmembers causes a left or right end portion of the pressure-receivingmember to move from an initial position toward an advanced positionforward of the initial position, or from the advanced position towardthe initial position; and a connecting wire disposed along a backsurface of the pressure-receiving member to connect thepressure-receiving member to the left and right link members, whereinthe pressure-receiving member comprises a pressure-receiving portionwhich faces a back of the occupant, and left and right support portionsextending from left and right ends of the pressure-receiving portionlaterally outward and frontward, wherein each of the left and right linkmembers comprises: a first link member supported at the correspondingside frame; and a second link member that connects the first link memberand the connecting wire, the second link member being disposed rearwardof a corresponding support portion, and kept out of contact with thecorresponding support portion.
 2. The vehicle seat according to claim 1,wherein part of the connecting wire is disposed between the second linkmember and the corresponding support portion as viewed from a directionparallel to an axis of the swinging motion of the left or right linkmember.
 3. The vehicle seat according to claim 1, wherein part of theconnecting wire is disposed between an axis of a swinging motion of thesecond link member and the corresponding support portion as viewed froma direction parallel to the axis of the swinging motion of the secondlink member.
 4. The vehicle seat according to claim 1, wherein theconnecting wire includes left and right bent portions provided at leftand right end portions thereof, the left and right bent portions eachextending in a direction away from a corresponding support portion, andeach of the left and right bent portions being connected at left orright end thereof, to the corresponding second link member.
 5. Thevehicle seat according to claim 4, wherein each of the left and rightbent portions is located at a distance from the corresponding supportportion, and when a rearward load not less than a predeterminedmagnitude is applied from an occupant to the pressure-receiving memberand causes the support portions to deform rearward, each of the left andright bent portions contacts the corresponding support portion.
 6. Thevehicle seat according to claim 4, wherein each of the left and rightbent portions is so located as to be always in contact with thecorresponding support portion from rearward.
 7. The vehicle seataccording to claim 4, wherein each of the left and right bent portionsis so located as to be contactable with a laterally outer end portion ofthe corresponding support portion in the advanced position fromrearward.
 8. The vehicle seat according to claim 1, further comprising aheadrest, wherein the seat cushion comprises a seat cushion frame, aseat cushion pad, and a seat cushion outer covering, the seat cushionframe being upholstered with the seat cushion pad and the seat cushionouter covering, wherein the seat back comprises a seat back frame, aseat back pad, and a seat back outer covering, the seat back frame beingupholstered with the seat back pad and the seat back outer covering, andwherein the seat back frame comprises the left and right side frames, anupper frame connecting upper portions of the left and right side frames,and support brackets to which the headrest is attached.
 9. The vehicleseat according to claim 8, wherein the seat back frame further comprisesa lower frame, and is formed in a shape of a picture frame with theupper frame, the left and right side frames, and the lower frame joinedtogether.